The present disclosure is primarily directed toward applications in an aircraft jet engine. The device may be arranged for controlling air bleed. In known aircraft jet engines, a bleed passage extends between the primary gas duct and the secondary gas duct in order to bleed air from the primary gas duct to the secondary gas duct. In certain operational conditions, compressed air is bled from the primary gas duct via the bleed passage and introduced in a high speed gas flow in the secondary gas duct.
Such an air bleed device may be arranged in a fan hub frame of the engine. A plurality of openings run through the primary gas duct wall at mutual (equal) distances in the engine circumferential direction. The annular member surrounds the primary gas duct and a plurality of the moveable elements are arranged for both closing and opening the bleed openings. More specifically, the annular member is arranged on an opposite side of a casing wall relative to the moveable closing element. This should be regarded as a preferred, but not limiting application of the device.
In the context of the present disclosure, the term “jet engine” is meant to include various types of engines, which admit air at relatively low velocity, heat it by combustion and shoot it out at a much higher velocity. Accommodated within the term jet engine are, for example, turbojet engines and turbofan engines. The invention will be described below in an embodiment for a turbofan engine, but may of course also be used for other engine types.
According to a previously known air bleed system, the link member for transmitting the motion to the moveable closing element extends from the annular member through an opening in a casing wall to the moveable closing element. A large amount of the torque from the annular member was transmitted via the link member to an articulation joint during operation, which led to wear of the parts of the articulation joint.